<template>
  <div>
    <router-link tag="div" class="header-abs" to="/" v-show="showAbs">
      <div class="iconfont header-abs-iconfont">&#xe624;</div>
    </router-link>
    <div
      class="header-fixed"
      v-show="!showAbs"
      :style="opacityStyle"
    >
      <router-link to="/">
        <div class="iconfont header-fixed-back">&#xe624;</div>
      </router-link>
      景点详情
    </div>
  </div>
</template>

<script>
export default {
  name: 'DetailHeader',
  data: function () {
    return {
      showAbs: true,
      opacityStyle: {
        opacity: 0
      }
    }
  },
  methods: {
    handleScroll: function () {
      const top = document.documentElement.scrollTop

      if (top > 60) {
        let opacity = top / 140

        opacity = opacity > 1 ? 1 : opacity
        this.opacityStyle = {
          opacity
        }
        this.showAbs = false
      } else {
        this.showAbs = true
      }
    }
  },
  activated: function () {
    window.addEventListener('scroll', this.handleScroll)
  },
  deactivated: function () {
    // 解绑window这个事件
    window.removeEventListener('scroll', this.handleScroll)
  }
}
</script>

<style lang="stylus" scoped>
@import '~styles/variable.styl'
.header-fixed
  z-index: 2
  position: fixed
  top:0
  right: 0
  left: 0
  height:$headerHeight
  line-height:$headerHeight
  text-align: center
  color: #fff
  background: $bgColor
  fonfont-size: .32rem
  .header-fixed-back
    position: absolute
    top:0
    left:0
    width:.64rem
    text-align: center
    font-size:.4rem
    color: #fff
.header-abs
  position: absolute
  left:.2rem
  top:.2rem
  width:.8rem
  height:.8rem
  text-align:center
  line-height:.8rem
  border-radius:.4rem
  background: rgba(0,0,0,.7)
  .header-abs-iconfont
    color: #fff
    font-size:.4rem

</style>
